Spark plug



Dec. 8, 1925.

` 1.564.645 J. M. THOMAS SPARK PLUG Filed Nov. 30. 1923 /NVE/vo/P JESSEM, #forms /0 wg mw Arrow/ns Patente-d Dec. 8, 1925.

isaias- UNITED STATES P'iA-:TENT-` OFFICE.

JESSE M; THOMAS, 1OFl-"hll LAWN, MISSOUR, ASSIGNOR OF VONE-'lI-IIRD 'TO`WJLLIAM D. GIEtUEILLIEv,V OF ST. `ll'.i0llV]S, MISSOURI.

SPARK PLUG. i

Application filed November 30, 1923.5- Seral No. 677,678.

fo all whom` it may concern.'

Be it known that I, JnssnM. THOMAS, a citizen of the United States ofAmerica, a resident of Pine Lawn, in the county "of St. Louis, State ofMissouri, have inventedfeertain newy and useful lmprovementsinV SparkPlugs, of which thel following 'is 1 a full,

clear, and exact description, reference/.being .1 had to theaccompanyingdrawing, formingA- a part of this specification.`

This invention relatesv to` improvements.

in electric ignition devices,` commonly called spark plugs, for internalcombustion engines,'and it consists in the novel features, 'structureand combination of parts'hereinafter describedand particularly pointedout in the claims.-

The object of the invention is, generally speaking, to provide a sparkplug which may be conveniently*manufactured and composed of a limitednumber of parts, and' in operation be highly efficient and reliable, andmore specifically the object of the invention is to provide a sparkplugjjcomprising a main exterior casing and an interior unit including acore, or body, within said main exterior casing. The main exteriorcasing is screwed into a wall of an'engine cylinder, and the interiorunit is so arranged that it may be rotated axially relative to said mainexterior casing without moving said main exterior casing, thus renderingitpossible' to secure the spark plug in place in a wall of an internalcombustion engine after. which the interior unit may be rotatedindependently of the main exterior casing so "that a predeterminedportion of said interior unit' may be faced toward a designated part ofsaid internal combustion engine..

The spark plug disclosed in the present application is particularlyintended for use with the improved shield for spark plugs disclosed byme in Aan application for United States Letters Patent iiled Novemberll, 1022, and bearing Serial Number 600,265;

`With the foregoing and other objects in view, the invention comprises.the novel construction, combination "and arrangement of partshereinafter more specifically 'described and illustrated in theaccompanying drawings wherein is shown the" preferred embodiment of theinvention; However,'it is to be understood that the inventioncomprehends changes, variationsand modifications which come within thescope ofthe claims hereunto appended;

Figpl is a Afront elevation of myimproved,

Fig. TV is laperspective View of theshield I associated with. inyimproved spark. plug.i ln the drawing, A designates my improved sparkplug` which comprises a main 'exterior casuigfB and an" insulatinggcore,orbody, C. The main exterior casing B is provided with a threaded lowerportion D anda non# circular wrench-receivingfportion E wherebylsaidmain exterior casing may be screwed into an internallyV threaded'opening in a wall of an internal vcom'bustioi'i engine.v The mainexterior casingB is, as'usual, formed of metal, and 'saidl main exteriorcasing is provided .with internal screw threads F, as shown indrig.V Il.A main exterior' casing'B is a horizontal annular shoulder l, whichfisarrangedbelow the internall screw threads F justinentioiied.

Located within. the main exterior Acasing B isfaninterior"core4supporting device 2,Y

said supporting.device` being constructed of metal and being inthe formof a shell havingan' elongated cylindricalupper portion 34 and ai lowercylindrical portion 4.' An annular horizontal-wall. 5 connects theannularwallof the upper portion of thc shelll with'the anniilai'wvall ofthe lower portion thereof. When the'spark plug is assembled' the 'lowerface of the horizontal annular' wall 5 ofthef core-supporting de-r vice2 restsupon the shoulderl within the main exterior casing B, there'beinga gasket 6 interposed between the opposed faces of said shoulder and'said wall.

Theinsulating core 'or bodyC is arranged partially within the mainexterior casing B", said core or body being extended above ing core'orbody C is provided with an en'- larged portion C', which is arrangedwithin the enlarged upperportion 3 of the coresupporting'device 2, asshown in F-igj IIJ In assembling the spark' plugyan annular gasket?is'interposed between the lowerv face of theenlarged portion C" ofthecore'l C andthe top" face 'of the'horizontal vwall 5y ofthecore-supporting-'device 2? Theupper Arranged within the end of thecore-supporting device 2 is provided with a comparatively thin annularwall 2', which secures the core C to the coresupporting device 2. Thisannular wall is bentI inwardly so that it overlaps the outer portion ofthe enlarged portion of the core C, as shown in Fig. II. An annulargasket 7 is interposed between the bent-over annular wall 2 and the topface of the enlarged portion of the core C. The reason for the gaskets6, 'T and 7 is that the core C is made of an insulating material, suchas porcelain, which is usually easily broken, and the gaskets formcushions between said breakable body and the hard metallic parts withwhich it contacts. An electrode Gr passes through the 'core C andextends downwardly therefrom, said electrode being provided with-abinder nut G by which a conductor terminal may be held in contact withsaid electrode.

8 designates a threaded bushing which is provided with external screwthreads. In the assembled spark plug the threaded bushing 8 is screwedinto the interiorly threaded upper portion of the main exterior casingB, the lower end of said bushing bearing against an annular face 9 ofthe core-supporting device 2.

S designates a shield which is extended upwardly into t-he main exteriorcasing B and secured to the lower cylindrical portion et of thecore-supporting device 2. The shield S comprises a substantiallycylindrical member preferably constructed of spring metal, theannular-wall of said member being split, as shown most clearly in F ig.V, whereby said member may expand and contract. The shield S is providedwith a pair of outwardly extending ears l() which are in contact withthe lower end of the main exterior casing B, when said shieldhas beenextended the proper distance into said main exterior casing, and 'saidshield is provided with a pair of angularly projected members' ll whichare located at the lower end of said shield. Located in the wall of theshield S is an air opening l2, said air opening being provided with anair deflector 13. The air opening and air deflector are formed bycutting a U-shaped slit in the wall of the shield and bending the metalwithin said U-shaped slit inwardly to form the air detlector. Located inthe wall of the shield S adjacent to the upper end thereof is a pair ofapertures 1% arranged diametrically opposite to each other,` andarranged on the lower portion 4L of the core-supporting device 2 is apair of pins l5, said pins l5 also being located diametrically oppositeto each other. To attach the shield. S to the spark plug the upper endportion of said shield is introduced into the lower portion of the mainexterior casing Il. The shield is then moved upwardly until the lowerend of the coresupporting device 2 passes into the upper end of theshield. The ecges of the pins 15 are slightly rounded so 'that when theupper edge of the shield. contacts with said pins said shield will bespread so that said upward movement of said shield relative to said pinsmay continue until the ears l() contact with the lower end of the mainexterior easing B. lVith the shield in the position described a rotarymovement of said shield will bring the apertures lei to positions wherethey register with the pins l5, thus permitting said pins to extend intosaid apertures whereby said shield is firmly fixed to saidcore-supporting device 2. The angularly arranged projections 1l functionas YelectrodesA and when the spark plug is fully assembled with theshield in place, spark 0aps are provided between said angularlyarranged. projections ll and the electrode G, as shown in l? ig. I.

In the use of a spark plug provided `with the shield shown and describedherein, earbureted air will be drawn througli the air opening l2 andwill be de'tlected by the deileetor 13 against the liring points of theelectrodes to keep said tiring points of the electrodes clean. To obtainthe best results it is necessary that the open portionof said shield befaced toward the inlet valve of the internal combustion engine withwhich the spark plug is associated. Heretofore it has been necessary toscrew the ordinary spark plug into the opening in the wall of the engineand after said spark plug was firmly seated to place iark ci' some sorton that portion of the upper portion of the spark plug" which faced the.inlet valve of the engine. The spark plug would then be removed fromthe engine and the shield would be attached to said spark plug so thatthe open portion of said shield was en the same side of the spark plugas the mark. then the spark plug was again placed in the engine afterthe procedure just recited the open port-ion of the shield would beproperly positioned relative to the inlet valve of the engine. Myimproved spark plug is provided with a mark such as that indicated inFig. I by the reference character H. The apertures la in the wall of theshield S and the pins l5 on the portion l of the core-supporting device2 are so arranged that the open portion of said shield will be on thesame side of the core as the mark I-I when said shield is secured tosaid core-sup` port-ing device. To locate my improved spark plugproperly within an engine cylinder, the assembled spark plug is screwedinto the internally threaded opening in a wall of the engine as wouldany other spark plug. It lmay then be found 'that Ythe marl; Il andconsequently the open portion of the shield S are not 'facing the inletvalve oiv the ei'igine. In that event it is only necesllO sary tounscrew the threaded bushing o so that the pressure of said bushing isremoved from the face 9 of the corc-si'ipporting device 2. It will beremembered that the core-supporting device is'securely fixed to the coreC so that said core may not rotate while said core-supporting device isgripped between the lower end of the bushing S and the annular shoulderi, but when the pressure has been relieved by unscrewing the bushing,the'core C, core-supporting device 2 and shield S may be freely rotatedas a single unit. The core may therefore be rotated until the mark H-faces the iniey valve of the engine, in which position the shield S willbe properly positioned with relation to said inlet valve. After the coreC has been properly positioned the threaded bushing 8 will be screweddownwardly until the lower' end thereof' bears firmly against thecore-supporting device 2, whereby said core-supporting device will befirmly gripped between the lower end of said bushing and the shoulder l,thus preventing accidental movement of said core. lt will be noted thatthe lower end of the bushing 8 bears against the metalliccore-supporting device 2, consequently there is very little danger thatthe core C will be cracked when said bushing is screwed downwardly toclamp said core in place.

I claim:

l. A spark plug comprising an exterior member adapted to be secured in awall of an engine, an interior unit within said exterior member, saidinterior unit including a core, an electrode supported by said core anda shield provided with a second electrode, said shield being arrangedadjacent to the lower end of said lirst mentioned electrode and beingprovided with a deflector adapted to deflect carbureted air against thefiring points of said electrodes, said interior unit being rotatableaxially relative to said exterior member and means whereby said interiorunit may be retained in a fixed position relative to said exteriormember.

2. A spark plug comprising an exterior member adapted to be secured in awall of an engine, an interior unit within said exterior member, saidinterior unit comprising a core, an electrode supported by said core, acore-supporting device and a shield provided with a second electrode,said shield being arranged adjacent to the lower end of the firstmentioned electrode and being removably attached to said core-supportingdevice and said shield being provided with a de'iiector adapted to deectcarbureted air against the firing points of said electrodes, saidinterior unit being rotatable axially within said exterior member, andmeans whereby said interior unit may be retained in a fixed positionrelative to said exterior member.

3.A spark plug comprising` an exterior i member adapted ,to be securedin a wall of an engine, an interior unit within said exterior member,said interior unit comprising a core, an electrode supported by saidcore, a core-supporting device to which said core is lixed and a shieldprovided with a second electrode, said shield being arranged adjacent tothe lower end of said first mentioned electrode, and means whereby saidshield is removably attached to said coresupporting device, said meanscomprising pins arranged on said core-supporting device which pins areadapted to enter apertures in the wall of said shield, said interiorunit being rotatable axially within said exterior member and meanswhereby said interior unit may be retained in a fixed position relativeto said exterior member.

el. A spark plug comprising an exterior member adapted to be secured ina wall of an engine, an interior unit within said exterior member, saidinterior unit comprising a core, an electrode supported by said core, acore-supporting device to which said core is fixed, a shield providedwith a second electrode, said shield being arranged adjacent to thelower end of said first mentioned electrode7 and means whereby saidshield is removably attached to said coresupporting device, said meanscomprising pins-arranged on said core-supporting device which pins areadapted to enter apertures in the wall of said shield, said shield beingprovided with an aperture through which carbureted air is drawn againstthe firing points of said electrodes, said interior unit being rotatableaxially within said exterior member, and means whereby said interiorunit may be retained in a fixed position relative to said exteriormember.

5. A spark plug comprising an exterior member adapted to be secured in awall of an engine, an interior unit within said exterior member, saidinterior unit comprising a core, an electrode supported by said core, acore-supporting device to which said core is fixed, a shield providedwith a second electrode, said shield being arranged adjacent to thelower end of said first mentioned electrode, and means whereby saidshield is removably attached to said coresupporting device, said meanscomprising pins arranged on said coresupporting de-` vice which pins areadapted to enter apertures in the wall of said shield, said shield beingprovided with an aperture through which carbureted air isl drawn againstthe firing points of said electrodes, and a deflector on said shieldadjacent to said aperture, said interior unit being rotatable axiallywithin said exterior' member and means whereby said interior unit may beretained in a xed position relative to said exterior member.

llO

6. A spark plug comprising an eXterior member adapted to be secured to awall of an engine, an interior unit Within said exterior member, Saidinterior unit including a core, an electrode supported by said core, :Lsecond electrode, and a shield, said shield being larranged adjacent tothe lower end of the first mentioned electrode and being provided with adeflect-or adapted to deflect earbureted air against the firing pointsof seid electrodes, said interior unit being rotatable axially relativeto said exterior member, and means whereby said interior unit may beretained in a fixed position relative to said exterior member.

In testimony that I claim the foregoing I hereunto affix my signature.

JESSE M. THOMAS.

